Size of a Sky Dome!

From: Alex Ferguson <abf_at_cs.ucc.ie>
Date: Tue, 31 Mar 1998 02:48:20 +0100 (BST)


Mikael Raaterova on stellar parallax:
> The problem with what Alex suggested is that it measures objects in the
> sky, not the Sky Dome itself. If all celestial objects were glued to the
> Sky Dome it would work, but what says that they are?

That's true. But this would likely perefctly satisfy, say, a Dara Happan Materialist, who presumably would hold to his culture's belief that the stars _are_ glued to (or rather, holes in) the Sky Dome.

> Also, wouldn't the Sky (being water) be affected by the tidal forces of the
> Blue Streak, making it's distance variable?

I don't think the Sky _is_ water, but granted there must be some residual amount swilling around from that nasty Lorion incident. I doubt that Sky Quakes are a _huge_ source of inaccuracy... (that is, not compared to all the other sources).

Joerg:
> As far as I am concerned, the Sky Dome looks like a perfect hemisphere with
> 50 km (or 80 km, if you prefer imperial measures) wherever you look at it -
> probably even wrt parallax.

It's not at all clear to me what this statements means, even observationally, leaving aside Cosmologically. Are are you saying that the Sky always looks the same from any given location (which is infinite parallax), or that they vary in some Mysteriously Unstated way. Clearly, you can't be claiming that they have the parallax of objects 50 (or 80) km away, if they always form a "perfect hemisphere".

> The most interesting question is the location of items below the star/sky
> dome, like the Red Moon (the lowest of the stellar bodies, unless you count
> the Zenith), the planets, special phenomena (Orlanth's Ring, the Juggernaut)
> and the sun.

Apart from the Red Moon and Zenith, ought any of these to have any significant difference in their apparent distance from the Sky Dome?

Slainte,
Alex.


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